In the drilling and operation of oil wells, a considerable amount of apparatus is often placed down the bore holes. (Although the term "down" is used, some bore holes may have considerable lengths which are far from vertical, and may be substantially horizontal). There can be considerable flows of material trough the bore hole, such as mud used for driving drill heads, and wires or pipes may be passed through the bore hole. Further, the bore hole may pass through friable strata which may be eroded. All these matters can result in the accumulation of detritus, which will here be termed "mud", in the bore hole; its consistency may of course vary widely. The mud may be deposited along the length of the bore hole, or on top of a piece of apparatus in the bore table.
It is often desirable or necessary to clear a bore hole of such mud. Present techniques for such clearing are relatively primitive. Some form of scraper or similar mechanical device may be lowered into the bore hole in an attempt to loosen compacted mud, and some form of bucket or similar mechanical device may similarly be lowered into the bore hole in an attempt to capture particles or pieces of mud and pull them up to the surface.